Circuit breaker



July 3, 1928. V v C. E. ANDERSON cmcu'n' BREAKER rmaq'ul 17'. 1925 2 Sheets-Sheet 1 w T N v W CARL Ema "hoe/es! ATTORN EYS July 3, 1928.

1,675,322 c. E. ANDERSON CIRCUIT BREAKER Filed July 1'7, 1925 2 Shets-Sheet 2 INVENTOR C'flkL ERIC qrvncnsou JM 7 ATTORNEYS Patented July 3, 1928.

UNITED; STATES, PATENT OFFICE.

CARL ERIC ANDERSON, OI STRATI'OBD, CONNECTICUT, ASBIGNOR TO THE BRYANT ELECTRIC COMPANY, OF, BRIDGEPORT, CONNECTICUT, A. CORPORATION OI CON- NECTICUT.

cmcon BREAKER.

Application na m 17, 1925. Serial m. 44,302.

My invention relates to circuit breakers, and particularly to a circuit breaker which is both manually and thermostatically operated to' open the circuitcontrolled thereby.

Among the objects of my invention are first, to reduce the mechanical stress 'imposed upon the thermostatic element; second, to so arrange the mechanism that'such stress as is imposed upon the thermostatic elemen-t places the latter under tension rather than under compression; third, to provide means for resetting the thermostatic trip mechanism while the circuit is open; fourth, to provide a simple and efficient general layout of the circuit breaker for accomplishing my objects above stated and-fifth,various features of detail hereinafter described or shown in the accompanying drawings, in which Fig. 1 is a plan view of a circuit breaker ifn which my invention is embodied in 'one orm;

Fig. 2'is a similar view showing the position of the parts on automatic opening of the circuit;

2 v Figs. 3 and 4 are sections on the lines 33 and 4-4, Fig. 1, respectively.

In circuit breakers of the type to which this invention relates, it has been proposed to provide a circuit-opening mechanism which comprises a thermostatic element. In

the prior construction the thermostatic element in its normal position, directly supports a-member which is subjected to heavy stress by the operating spring of the circuit breaker mechanism. This is objectionable, since the thermostat may soften somewhat under the heating action of overload current, and the pressure exterted thereon tends to buckle the element. A permanent set results which interferes with the proper functioning of the element. Moreover, the normal warping of the thermostat which withdraws it from supporting position, must be effected against the frictional drag 4 imposed upon the parts under the strem of the circuit breaker spring. This frictional drag brakes thegoper'ation of the thermostatic element, necessitates Iheavier overload to warp it, and consequently increases the danger of overloading and buckling. By my invention I not only change -the effort exerted upon the thermostatlc element from a compression effort to a tensiomefiort, but I greatly reduce the braking effort. To

efiect these results I provide between the thermostatic element and the circuit breaker mechanism a trip device so located and interposed between these parts that the stress exerted upon the thermostatic element is not only minimized, but also exerted in a direction to tension the same. The mechanism is thus rendered far more sensitive to overload, and the danger of imparting a permanent abnormal set to the thermostatic element is eliminated.

Referring to the drawings, I have illus trated my invention in a circuit breaker of the general type shown in the patent to myself and one William H. Keefe, Jr., No. 1,656,851, dated January 17, 1928, and in the copending application by myself and one William H. Keefe, Jr., Ser. No. 45,834 filed July 24, 1925, pertaining to certain features of the mechanism other than those to which my sole invention is directed. The circuit breaker, as here shown, comprises a base 15 of insulating material, upon which is mounted a cover 16 with insulating lining 17 to house in the thermostat and the circuit breaker mechanism. Line terminals 18 and 19 project beyond the switch base and are respectively connected to the housed stationary switch contacts 20 and 21 through intermediate conductors, as hereinafter explained in detail. The circuit-closing block 22 which is adapted 'to bridge the contacts 20 and 21, is mounted on a rock lever 23 pivoted at 24 (Fig. 2) in the crotch of the V-shapedframe 25, and playing between the opposite sides of the V-opening. The frame 25 is pivoted at 26 in the stationary bracket 27 secured in any suitable manner to the base 15.

Cooperating with the rock lever 23 is a yoke member 28 pivoted at 29 (Fig. 3) on the bracket 27 and connected by a pull spring 30 to the rock lever. A. spindle 31, secured to the yoke 28, rojects through the cover 16 and carries t e operating thumb piece 32. Upon manual oscillation of the atter'the yoke 28 is swung on its axis, thus causing the attached end of spring 30 to shift from one side to the other of the pivot 24 of the rock lever 23, and thus exert its stress in a direction to throw the "rock lever across the V-opening-in the frame 25 to 0 on or close the circuit in a, manner well on erstood in the art.

times by the catch 37 mounted at the free end of the U-shaped thermostatic element 38. Inasmuch as the yoke 28 is mounted-upon the fixed bracket 27, the operating spring 30 constantly exerts, through the rock lever 23, an effort hpon the pivoted frame 25, causing the lug 33 to bear upon the trip lever shoulder 34 and thus stressing the latter in avdirection to cause :the free end of the trip lever to bear against the catch 37 of the thermostat 38. The eiiortthus exerted upon thethermostatic element places the latter' under tension. Moreover, the stress exerted upon the thermostat through the trip lever 35 is very slight, by reason of the fact that the flame supporting shoulder-'34 is adjacent the pivot 36, and the distance. therefrom to its free end, which engages the catch 37 is many greater than the distance between the shoulder-'34 and the pivot point 36. The trip lever is thus a lever of the third-class, in which the power is applied close to the fulcram point, and the efl'ective efiort of which at the distant point of load, is very slight. Consequently, thefrictional braking e ort exerted by the trip leyer upon the catch 37, upon the warping displacement of-the thermostatieelement is reduced to a Since the operation of the thermostat is thereby rendered very sensitive, danger of overheating is very. shght, and even if overheating should occur, the mechanical stress 9n thethermostat is not only slight but also in tension. No permanent setin buckled condition can occur and the ,danger of deformation by elongation is practically ml;

The position of the arts when the thermostatic element has n warped out of normal sition by current overload,"'is indlcated m Fig. 2 The warping'of the thermostat withdraws the catch 37 from the end of the trip level-:35, and the latter now disimder the stress of sprin engaged atjts free end' away from the thermostat under thd effort of the spring 30 exerted through the frame lug 33 against the shoulder 34. The lug 33 escapes the shoulder and the frame swmgson its pivot, 30, until halted bythe stop lug 39. In this position the circult is opened by the combined action of the 7 frame 25, which positively forces i the rock lever ont of circuit-closing position,and further by the throw of the rock lever across the V-opening of the frame 25.

. The shift ofthe pivot oint 24 of,the rock lever across the planeo effort of the spring '30 causes the spring to swing the yoke 26 toward'its open-circuit position, The oke 1S halted, however, intermediate position by the stop lug 40 on theframe 25, so that" the handle 32 which moves with the yoke 00- cupies'an intermediate indicating position, as

set forth in thecopending joint applications above mentiohed. v To return the parts to normal posltion,

r the thumb piece '32 is moved ,to the position which it occupies when manually operated to open-circuit position. This causes the yoke 28 to swing to the left (Fig. 2),

with it the frame 25 and causing the lug thereof tojengage the nose 41 of the trip 1 when the thumb piece 32 released so that I the efi'ort of the spring 30 is again exerted through the lug 33 of theframe upon the shoulder 34'of the trip.

' .The circuit connection between the terminal 18 and the contact 20 is'traced as-follows;

from the inner end of the terminal 18, through screw bolt 42 to bracket 43 (Fig.4), through.

leg a of the U-shaped thermostat to leg 6 of the. thermostat, thence through bridge 44, through screw 45', shunt 46 and screw; 47 to contact 20. The circuit from terminal 19 follows a course through screw 48 to the base of contact21. y Such and other modified arrangements will doubtless occur tothose dealing with the roblem, which nevertheless embody the unerlying thoughts which I claim as myin- 'ventlon.

trip lever'may be replaced' by a cup ofmultiplying levers but. this comphcatlon I have folln Again it will be reco 'noized that by reduc ing in some such fas on as indicated, the

efiz'ortexerted by the circuit breaker spring 1 i i rather than in. tension; without 'reducingit's unnecessary and undesirable.

It will of course be obvious that the single Y sensitivity to overload currentorcausmg the element to buckle when softened by heat.

I claim-e 1 1; A circuit breaker mechanism including v b a movable member, a springstressing same constantly to open-circuit position, a swinging support for said movable member, and a warpingthermostatic element operatively engaged under tension by said support when the arts are in normal position, but autoto permit its displacement by the movable member under the stress of said spring. 2 .-.A circuit breaker mechanism comprismatlcally'releasing the support on overload ing a movable member, aspr' stressing 1 the same constantly to open-circuit'position, awarpm thermostatic element and a stress-' minimizing swinging support for said movable member operatively engaging the thermostatic element under tension when the parts are in normal position, but automatically swinging out of supporting position when released by the thermostat on overload.

3. A circuit breaker mechanism comprising a movable member, a spring stressing the same constantly to open-circuit position,

a warping thermostatic element and a stress m1n1m1z1ng swinging support for said movable member operatlvely engaging the thermostaticv element under tension when the fort of its associated spring, an overload de-.

vice normally maintaining said trip device in ppsition to support said pivoted member but eeing the latter on over load to permit the displacement of said pivoted trip device under the effort of said spring-stressed member and manual l operated means for-restoring said trip device and pivoted member to normal sition.

5. a circuit breaker, a pivoted frame,

a manually operated circuit opener pivoted thereon, a spring stressing said circuit opener against the frame, a dls laceable member normally supporting the ame, and a thermostat normally engaging said displaceable member but-freeing the latter on overload to permit its displacement under the effort ex- .erted thereon by the frame undi' the stress of the spring energizing the circuit opener.

manually operated circuit opener pivoted thereon, a spring stressing. said-circuit opener against the frame, a displaccable member normally su porting the frame, a'warping 'U shap'ed thermostat normally engaging said displaceable member but freeing the latter on overload to permit its displacement under the effort exerted thereon by the frame under the stress of the spring energizing the circuit opener.

7. In a circuit breaker, a pivoted frame, a'

pivoted latch arm having a supporting shoulder adjacent itspivot for the engagement of said 'frame thereon, and a latching nose at a point remote from the pivot, a warping thermostat normally engaging said latching nose to maintain the latch in frame-supporting position, together with a circuit opener pivoted on the frame, between the circuit stressing the latter against the latch.

and a spring interposed-- opener. and frame and 6. In a circuit'breaker, a pivoted frame, a

In testimony whereof I have signed my name to this ification.

, 8&1; ERIC ANDERSON; 

